Torrentó, C.* ; Ponsin, V.* ; Lihl, C. ; Hofstetter, T.B.* ; Baran, N.* ; Elsner, M. ; Hunkeler, D.*
Triple-element compound-specific stable isotope analysis (3D-CSIA): Added value of Cl isotope ratios to assess herbicide degradation.
Environ. Sci. Technol. 55, 13891-13901 (2021)
Multielement isotope fractionation studies to assess pollutant transformation are well-established for point-source pollution but are only emerging for diffuse pollution by micropollutants like pesticides. Specifically, chlorine isotope fractionation is hardly explored but promising, because many pesticides contain only few chlorine atoms so that "undiluted" position-specific Cl isotope effects can be expected in compound-average data. This study explored combined Cl, N, and C isotope fractionation to sensitively detect biotic and abiotic transformation of the widespread herbicides and groundwater contaminants acetochlor, metolachlor, and atrazine. For chloroacetanilides, abiotic hydrolysis pathways studied under acidic, neutral, and alkaline conditions as well as biodegradation in two soils resulted in pronounced Cl isotope fractionation (εCl from -5.0 ± 2.3 to -6.5 ± 0.7‰). The characteristic dual C-Cl isotope fractionation patterns (ΛC-Cl from 0.39 ± 0.15 to 0.67 ± 0.08) reveal that Cl isotope analysis provides a robust indicator of chloroacetanilide degradation. For atrazine, distinct ΛC-Cl values were observed for abiotic hydrolysis (7.4 ± 1.9) compared to previous reports for biotic hydrolysis and oxidative dealkylation (1.7 ± 0.9 and 0.6 ± 0.1, respectively). The 3D isotope approach allowed differentiating transformations that would not be distinguishable based on C and N isotope data alone. This first data set on Cl isotope fractionation in chloroacetanilides, together with new data in atrazine degradation, highlights the potential of using compound-specific chlorine isotope analysis for studying in situ pesticide degradation.
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Publication type
Article: Journal article
Document type
Scientific Article
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Keywords
Chlorine Isotopes ; Degradation ; Hydrolysis ; Isotope Fractionation ; Pesticides; S-metolachlor; Chloroacetanilide Herbicides; Organophosphorus Compounds; Pesticide Degradation; Fractionation; Atrazine; Hydrolysis; Biodegradation; Carbon; Transformation
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Language
english
Publication Year
2021
Prepublished in Year
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2021
ISSN (print) / ISBN
0013-936X
e-ISSN
1520-5851
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Volume: 55,
Issue: 20,
Pages: 13891-13901
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ACS
Publishing Place
Washington, DC
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Reviewing status
Peer reviewed
POF-Topic(s)
20403 - Sustainable Water Management
Research field(s)
Environmental Sciences
PSP Element(s)
G-504390-001
Grants
BRGM funding (DEV REPERER project)
Swiss National Science Foundation (SNSF)
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Erfassungsdatum
2021-11-24